Electrical method and apparatus for injecting or propelling increments of fuel or other fluids



1948- x V A. GPBODINE, JR 2,436, 9

ELECTRICAL METHOD AND APPARATUS FOR INJECTING OR PROPELLING INCREMENTS OF FUEL OR OTHER FLUIDS Filed Sept. 12, 1941 2 Sheets-Sheet 1 I? ALBLRT 6. Bo0/-,de..

6r HARRIS, AIECH, Ras 7-5 6 HA ems w g FT/Azi to FIRM Feb. 17, 1948. BODINE, JR 2,436,090

ELECTRICAL METHOD AND APPARATUS FOR INJECTING 0R PROPELLING INCREMENTS OF FUEL OR OTHER FLUIDS Filed Sept. 12, 1941 Z-Sheets-Sheet 2 /N VAN 7'01? A LBERT 6. Boo/Ms, JR.

ATTOPN'K-S.

Patented. Feb. 17, 1948 OFFICE ELECTRICAL METHOD AND APPARATUS FOR INJECTING R PROPELLING INCRE- MENTS OF FUEL OR OTHER FLUIDS Albert G. Bodine, Jr., Burbank, Calii'., assignor to The Calpat Corporation, Los Angeles, Calif., a corporation of California Application September 12, 1941, Serial No. 410,5f8

In general, my invention will be exemplified with relation to an improved method and apparatus for delivering fuel to a heat engine and, more particularly, with reference to a fuel injection system, electrically actuated, for injecting fuel into the cylinder of a compression ignition engine in timed relationship with the piston. It should be clear, however, that the invention has other uses, and it is a general object of the invention to provide a novel method and apparatus for atomizing, metering, or propelling a liquid. or for intermittently discharging increments of fuel from a space. Another. important object is to provide for the intermittent delivery of increments of liquid through a passage with intervening periods of incremental ejection therefrom by use of an electric spark, whether or not aided by acoustic means.

One of the fundamental premises of the present invention involves the generation of a pressure surge by use of an electric spark. If an electric spark or are is established within a mass of liquid, for example, liquid fuel to be burned in a heat engine, a steep-wave-front pressure surge is generated which can be utilizedfor forcing an increment of fluid from the vicinity, of the spark into, for example, the cylinder of a com- Claims. (01. lea-P32) square inch, or more. It is an object of the present invention to develop a requisite high pressure electrically. It is also an object of the present invention to provide a system which does not necessarily require that the compressed air in "the cylinderat the time of fuel injection should be ata temperature in excess of the fuelignitlon temperature. As will be subsequently explained, use of my invention permits activation of the fuel to such a degree that compression ratios can sometimes be used which are lower than those now required to compress the air to a fuel-igniting temperature.

tion systems represent a, large portion of the total pression ignition engine. It is an important object of the present invention to provide a novel method and apparatus utilizing an electric spark v or are in this capacity. I

Compression ignition engines, commonly exemplified by the Diesel engine, operate on the principle of compressing a volume of, airin a cylinder to a fuel-igniting value, after which a small volume of fuel, accurately metered and timed, is atomized into the highly compressed air" for combustion and consequent expansion which forces the piston-inward. The expanded gases are subsequently discharged during the exhaust cycle. Themetering and injection of the fuel is a limitation on the power, speed, efiiciency, and

minimum size of such engine, and the present invention has among its objects a fundamentally different fuel injection system.

high cylinder pressure when the piston is at or near the end of its compression stroke. It is not an uncommon requirement for Diesel injectors to develop pressures from 5000 to 10,000 pounds per cost of the. engine and require all too frequent servicing to meet the requirement of accurate proportioning at high pressures. It is an object of the present invention to provide an electrical system in which extremely small increments of fuel can be accurately metered even at extremely high pressures. The meterable quantities are so small that it now. becomes practical to inject the increment of fuel at a plurality of positions within the cylinder through separate injector means, if this is desired, to combat ignition lag, improve fuel distribution within the compression zone, etc. The increment of fuel is then divided between the various injectors, and whil present-day in- V Ijection systems cannot accurately meter the extremely small increments thus required in a small Diesel engine, the present invention can be made so accurate in its proportioning of small quantities of fuel as to make this practical.

In the third place, it will be recognized that the injectionperiod is'of very short length, only a small fraction of the time it takes. the piston to move one stroke. For example, on a fourcycle Diesel engine, the injection must take place during 25 of crank-shaft rotation. Expressed in units of time, this amounts to a requirement that the fuel must be injected during a period of about /auo second, with a four-cycle engine running at a speed of 1200 R. P. M. In conventional Diesel engines, the fuel must both be metered and injected into the cylinder in such a short period of time. In my invention, the fuel can be metered and delivered to a spark chamher during, or throughout, the time that the piston is moving through its exhaust or intake stroke, the actual injection being caused by a timed spark or arc established within the spark chamber at the instant injection is desired. In other words,-the fuel delivery to the spark chamber can be at relatively low pressure and can extend throughout any portion of all of the complete cycle other than the actual period of injection. It is an important object of the present invention to provide such a system as it avoids the necessity of high pressure metering pumps with very short fuel-delivery strokes.

On the other hand, however, I may, if desired, forego the pumping action of the spark injector and use it mainly or only as a booster unit with present timed-pump injector systems. In other words, I may interpose m spark chamber near the nozzle of a conventional injection unit, with the result that the atomizing and activating action will reduce necessary pump pressures, and it is an object of the invention to provide such a system.

In the fourth place, the high pressure pump which forms a necessary part of present-day fuel injectors must be disposed at a distance from the point of introduction into the cylinder, being possible with conventional fuel injection systems,

as the injector piston cannot be stopped instantaneously, and even if it could, the compression of the fuel column and the expansion of the conduit connected to the cylinder would prevent such a sharp drop-off of pressure. In practice, it is found that a droplet of unatomized fuel remains in the atomizing nozzle as a result of the gradual drop-off in pressure, and this gives rise to numerous difficulties known to the art. It is an object of the present invention to avoid such difficulties due to dribble" and to insure that all fuel entering the cylinder shall be properly subdivided.

It is another object of the invention to provide a system for automatically cooling the sparkgenerating means to prevent any possibility of pre-ignition. At the same time, it is an object of the invention to initiate combustion at a position spaced from the electrodes generating the spark used for injection purposes so that these electrodes and the adjacent portions of the spark connected thereto by a small conduit or passage principle to smaller, higher-speed engines), there comes a time when the oscillations of the injector piston are largely absorbed in the fuel column and conduit. In addition, acoustic dlfllculties have been very troublesome in present-day injectors. It is an object of the present invention to eliminate all high pressure conduits of substantial length and to develop the injection pressure by electric means at a point very close to the cylinder itself. It is also an object of the invention, in some of its forms, to make use of acoustic principles as an aid to fuel injection.

In the fifth place, present-day compression ignition engines are limited by ignition lag with all of its associated difficulties. Attempted solutions from a standpoint of increasing compression pressures encounter limitations in bearing design, friction losses, etc. Attempts to solve this problem by trick combustion chamber shapes cluding appropriate activation of the fuel, appropriate distribution thereof in the cylinder, and, in some instances. the aiding of preliminary combustion by, introducing burning products into the cylinder ahead of or concurrent with the discharge thereinto of atomized fuel.

In the sixth place, present Diesel injection systems cause trouble due to dribble." In such engines, a pressure-time plot (pressure as ordinants and time as abscissa) covering the injection period would show an optimum, though theoretical, curve as follows. During the first portion of the injection period, a small amount of fuel should be delivered under gradually increasing pressure to instigate combustion, after injector of my invention will not become unduly overheated.

Another object'of the invention is to provide an injection-system adaptable for use with a wide range of fuels, some of which cannot be utilized in present-day systems because of their self-ignition' characteristics, difficult atomizing characteristics, or poor lubricating quality.

Still another object of the invention lies in the provision of an injection system providing an easily varied time of injection and an easily varied quantity of injection facilitating control of engine speed. The invention contemplates variou novel controls in this connection.

Various other objects and advantages will be apparent to those skilled in the art from the following description exemplifying several embodiments. The invention can take numerous forms, and those selected for illustration herein serve best to indicate the principles involved, though the showing has been simplified by a somewhat diagrammatic presentation without intent of limiting myself thereto.

Referring to the drawings,

Figure 1 is a diagrammatic view, partially in eration;

Figure 12 is a vertical sectional view of still another form of the invention.

'Asa background for a detailed description of the drawings, the following general principles should be kept 1h mind. 11 a volume of fuel oil is positioned in a confined space, and if spaced electrodes are disposed therein. a potential can be applied between the electrodes. Assuming that the potential is gradually increased, there will be substantially no current flow during the application of low potentials, though the fuel in the electrode gap will be subjected to progressively higher voltage gradients. When the potential is increased to the break-down value, an arc will be established between the electrodes. Thi are or spark represents a highly ionized electronic path of low resistance; and the arc will continue until the potential across the electrodes is reduced materially below the arc-establishing potential. This are will be of extremely high temperature and the result of striking an arc beneath the surface of such a fluid will be the immediate formation of a gas bubble within the electrode gap and through which the arcpersists. The gas bubble forms because of the vaporization or gasiflcation of at least some of the constituents of the fuel, the

are actually cracking some of the fuel and re- .suting in gas phase activation thereof.

Such a gas bubble forms with extreme rapidity and, of course, increases the pressure within the confined space. The rate at which this pressure increases is almost unbelievable. A very steepwave-front-pressure surge is thus generated with- -in the confined space, and it is such a. pressure surge that I use in the present invention for purposes of injection and atomization of fuel into the cylinder. In my system, the energy dissipated by the electric arc (hereinafter termed an electric spark) is used as a motivating force to iniect the fuel. An electric sp rk is one of the most eill- .cfent means for converting electrical energy into mechanical energy. Secondary functions of the spark are pulverizatlon and gasiflcation of the fuel, accurate control of timing of injection, and

- be equally clear that the pressure generated within such a confined space will not be caused appreciably by burning of the fuel therein, for the chamber will not contain oxygen to support such ;combustion. On the other hand, the electrically enerated force will be of such violence as to atomize the fuel as it flows to the cylinder, either with or without auxiliary atomizing expedients.

It will be also apparent that I can charge the confined space with a. fresh increment of fuel during any or all portions of the engine cycle between periods of injection, and that such incremental supply of fuel'to the confined space can be made under relatively low pressure conditions. correspondingly, the sequence is to charge theconfined space with a fresh increment of fuel, then establish the arc or spark to effect injection,

then recharge the confined space, etc.

Referring particularly to Figure 1, there is shown the upper end of a cylinder l cooperating with a removable head H to form a compression space l2, these elements being lacketed, if deacsaoco sired, for the passage of a cooling medium. The head It provides a threaded passage II for reception of the spark injector ll, details of which are shown in Figures 1 and 2.

This spark injector is shown as including a body I 8 providing a threaded shank received by the passage l3. The central portion of the body It is open to receive the lower end ll of a bushing I8 formed of insulating material, such as porcelain or other materials now common in the construction of spark plugs for gasoline engines. The bushing [8 provides a flange I! which is clamped against a corresponding ledge of the body l6 by a threaded insert 20.

The body is is, of course, grounded to the englue and carries a grounded electrode 22 which terminates preferably at or near the lower end of the lower portion ll of the bushing 13. This grounded electrode may be supported by the body It in various ways but, in the embodiment shown, this is done by a hood 23 at the lower end of the body 16 to define an intermediate chamber 24 at the'lower end ofthe bushing It. To provide communication between the chamber 24 and the combustion space I 2. I provide suitable passages through the hood 23. Three series of passages are shown, indicated respectively by the numerals 25a, 25b, and 250, for directing the fuel into the combustion space l2 at different angles with respect to the axis of the cylinder. Such passages or openings can be designed to direct the incoming fuel in any desired direction appropriate for insuring adequate and substantially complete mixing with the compressed air in the combustion space l2. As will be clear from the later consideration of Figures 6 to 12, the hood 23 and the chamber 24 formed thereby can be eliminated, thus permitting the fuel to be discharged directly into the compression space ii.

A fuel inlet member 21 provides a chamber 28 which receives liquid fuel through a check valve 29 from a source to be hereinafter described. Depending from the inlet member 21 is a tube 30 retained in a counterbore of a passage 3| extending through the bushing-i 8 so that the internal surface of the tube 30 forms an extension of the walls of the lower portion of the passage 3 I Threaded into the upper wall of the inlet member 21 is an electrode member 33 carrying an electrode 35 which extends downward through the tube 30 and passage 3! to terminate a short distance above the electrode 22. A small annular space 36 is provided between the electrode 35 and the walls of the tube 30 and passage 3|, through which the fuel may pass from the chamber 28 into the vicinity of the electrode 22.

To establish the spark between the electrodes 22 and 35 in timed relation with the engine, I may use a circuit such as shown in Figure 1 and which is representative in some of its aspects of conventional ignition circuits used on gasoline engines, though it will be designed for a greater power output. As shown, a battery 38 is connected in circuit with the primary winding 39 of a step-up coil 40 providing a high tension winding 4!. Included in the circuit between the battery 38 and the primary winding 39 is an ignition switch 42 and a 'make-and-break switch 43 actuated by a timing cam 44 and provided with a parallel-connected condenser 45. As is well known, when the contacts of the switch 43 open, a high voltage is induced in the secondary the other terminal is connected to the rotor of a distributor 41 through a conductor 48, The distributor has. peripheral contacts, one for each cylinder of the engine, a representative contact being indicated by the numeral 49 and being connected to the electrode member 33 by a conductor 50, The cam 44 is driven at a speed proportional to the crankshaft speed, as is also the rotor of the distributor 41. In the system shown, the contacts of the switch 43 would open during the time that the rotor of the distributor was in current-conducting relationship with each of the peripheral contacts thereof. A condenser Si is shown in the high tension circuit in parallel with the gap between the electrodes 22 and 35, and may be used if it is desired to establish oscillatory currents in this gap.

The liquid fuel can be supplied to the spark injector in any one of several ways. As will be later described with reference to Figure 5, the fuel may be delivered to the check valve 29 at substantially constant pressure, permitting fluid to flow to the passage 3| during any portion of the engine cycle when the pressure in the combustion space I2 is less than the supply pressure by an amount determined by the spring loading of the check valve 29. This is a system which can be used very successfully with the spark injector shown in Figure 1. However, the fuel supply illustrated particularly in Figure 1 is of the low pressure metering type. This may comprise a simple, low cost, low pressure, commercialtolerance version of a conventional fuel injection pump. It has the comparatively easy task of metering the desired fuel increment at relatively low pressures.

As shown in Figure 1, this pump includes a small cylinder 55 in which a piston 56 reciprocates under the action of a cam 51 driven at a speed related to that of the crank-shaft of the engine. During the downstroke of the piston 56, fuel is drawn from a tank (not shown) through a pipe 58 and enters the cylinder 55 through a check valve 59. The check valve 29 serves as the discharge check valve and may be positioned as shown in Figure 1 or adjacent the pumping means. As shown, the fuel displaced by upward motion of the piston 58 moves through a small pipe 60 connected to the check valve 29 by a small rubber hose 62 serving to insulate the pump means from the spark injector. The cam 51 can be designed to force fuel into the spark injector during or throughout the complete engine cycle except for the actual period of injection. correspondingly, instead of using a quick-acting high-pressure fuel injection pump, I may use a slow-acting low-pressure metering pump which serves only to deliver metered increments of fuel to the spark injector between periods of injection. Suitable controls known in the art of fuel injection, such as an adjustable by-pass to modify the effective piston stroke, can be used to vary the amount of fuel delivered to the spark injector during each stroke of the piston 56, thereby controlling the amount of fuel which will be later injected into the cylinder by the action. of the electric spark.

hi this embodiment of the invention, the confined space in which the spark is established may be considered as the chamber 28 and the passage 3|. If the flow of fluid fuel is downward toward the cylinder, this passage 3| should preferably be of capillary size in the sense that a descending .column of fuel will not flow therefrom when the lower boundary of this fluid column is in the position shown in Figure 3 or Figure 4.

The increments offuel delivered to the elec portion of the fuel, forms instantly and blows out of the lower end of the passage ii that increment of fuel below the electrode 35. An attempt has been made to indicate this action diagrammatically in Figure 2, where the spark is indicated by the numeral 65 and the expanding gas bubble by the numeral 66. The formation and expansion of the gas bubble is so rapid as to atomize the liquid fuel and mix therewith the vapors or gases constituting the gas bubble so that the intermediate chamber 24, defined by the hood 23, receives a mixture of all these constitucnts, which are then sprayed into the combustion space and appropriately distributed into the compressed air.

No actual combustion takes place in the gap between the electrodes, due to the absence of oxygen. The system can be designed to initiate combustion in the intermediate chamber 24, if used (by the action of the spark or by the existence in this chamber of compressed air at fueligniting temperature), or combustion may be delayed until actual discharge into the combustion space 12.

A spark between the electrodes 22 and 35 need 5 exist only instantaneously, though it can be extended throughout the period of injection. In either event, the conditions adjacent the electrode gap at the end of the injection period (and before supply of additional fuel to the spark injector) are shown approximately in Figure 3a, the lower end of the fuel column being now at or slightly above the lower end of the electrode 35. It is understood, of course, that .the high pressure surge developed by the spark will not force fuel upward in the passage 3| in view of the check valve 29 which entraps fuel in the chamber 28 and the passage 3|. Correspondingly, it is only necessary for the pump means to deliver an increment of fuel corresponding to that previously burned to the spark injector to bring the fuel column to the position shown in Figure 3. The difference in fuel volumes represented in Figures 3 and 3a represents the increment of fuel injected into the cylinder, and it will be understood that this increment is under the volumetric control of the pumping means formed by the cylinder 55 and piston 56. It will be understood, also, that the new increment of fuel delivered to the spark injector can be moved thereto relatively leisurely during the exhaust and intake strokes of the engine, and that the requisite pressure to cause flow of such increment of fuel will be relatively low. On the other hand, the spark injector can be used as a booster for a conventional high-pressure injector pump, as previously mentioned. For example, by changing the design of the cam 51 for short-period injection and establishing the spark during the injection period, the spark can aid atomization and activation of the fuel.

As mentioned above, the increment of fuel need ure 4, where the lower end of the'fluid column does not contact the electrode 22. As the voltage builds up between the electrodes, both the gaseous and liquid phases are subjected. to increasing voltage gradient until break-down occurs. The resulting spark will move through the gaseous and liquid phases in series but will still be formed within the fuel with in the contemplation of the meaning of that phrase in the present application. Establishment of the spark will vaporize a portion of the adjacent fuel and establish the pressure surge requisite for injection. In effect that portion of the fuel column below the electrode will be spewed into the intermediate chamber 24,, appropriately atomized, and mixed with some of the activated fuel constituents. Following the injection period, the column of fuel will terminate at or just above the electrode 35, as suggested in Figure 3a, and the subsequently introduced increment of fuel will again lower this column to the position shown in Figure 4 preparatory to'the next injection period. 1

Reference has been made in the above to activation of the fuel. This has reference, among other things, to electrical activation in the absence of oxygen and occurs as the result of the spark formed between the electrodes. Such electrical activation represents one of the important advantages of this invention. By use of the present invention, substantially all of the fuel comes in activating contact with the spark during prolished in the absence of an intimate mixture, or,

. if it is established in such a mixture, it will be in a mixture which is exceedingly rich in fuel constituents, so much so that combustion may be impossible before incorporation of additional air.

The third type of activation of which advantage may be taken in my system involves principles of acoustics. In this connection. it will be clear that the extremely steep-wave-front pressure surge instigated in my invention will give rise to pressure waves moving through the fluid in theconflned space. Resonant conditions within this space can be established by appropriate design. In addition, an oscillatory discharge across the gap can be used to establish or reinforce such pressure waves moving through the fuel in the confined space. 'Acousticwaves can be established or such frequency and amplitude jection into the cylinder and immediately before actual combustion. This is in contradistinction to the action taking place in a semi-Diesel engine in which a low intensity spark is formed in a combustible mixture in the cylinder to initiate combustion. In such an engine, only a small portion of the fuel can be affected by the spark, and a negligible amount of activation results. In such an engine, combustion is merely initiated by the spark, and most of thecombustion takes place by flame propagation.

Activation can be of any one or all of three types when usingthe present invention. Considering first that activation which takes place in the gap even in the absence of oxygen. it will be 7 clear that the spark temperature is so high as to both vaporize the adjacent fuel and actually crack a portion thereof, forming activated products aiding in the subsequent combustion.

The second type of activation may result when air is present in the vicinity of the spark even though not in the gap itself, as when operating as to resultin general molecular vibration at an energy level above that represented by the liquid phase energy level. These energy levels may extend to-that defined by the gasphase energy level and even upas high as the energy level representing bond breakage. Activating actions due to such acoustic vibrations become apparent particularly at liquid-gas interfaces. Considering, for example, the fuel-gas interface in Figure 4, even a relatively low level of acoustic energy will be sufficient to aid atomization, the action being as if the acoustic impulses projected molecules of the fuel into the adjacent gas. At higher energy levels, corresponding to those mentioned above,

activation proceeds rapidly. Considering the action which takes place at the interface of the gas bubble and the adjacent fluid when the spark is first formed, it will be apparent that similar principles apply and that the gas-vapor bubble will cause activation of the fuel at the interface, the activation persisting until the gas reaches the cylinder. In fact, the activation will persist until the succeeding injection period if, as is often desirable, a portion of the activated gas can be retained in the vicinity of the spark injector from one injection period to another. This is not difficult to accomplishes the hood 23 tends to retain a portionof the constituents last discharged from the passage 3| at the end of an injection period.

the invention, in accordance with the teaching of Figure 4. If a spark is established as there suggested, there will be a chemical action between the constituents of the air and the constituents of the fuel (or between the air and vapors resulting from the immediate or previous presence of an electric spark). This activation will take place prior to actual combustion, and the chemical action will consist predominantly of such activation, though a portion of the chemical action will consist in a partial oxidation resulting in organic oxides, such as aldehydes and alcohols. The activation resulting'in my system differs markedly from any negligible activation resulting in. semi- Diesel systems in which the zone between the electrodes is filled with a combustible mixture of air and fuel mixed in readily combustible pro- During the subsequent compression stroke of the engine, some air will enter the intermediate chamber 24 but will not displace an of the previous products. This is particularly true when operating the invention in accordance with the teaching of Figure 4, where the lowermost end of the fluid columnnever moves downward sufficiently to displace all gaseous products from the lowermost end of this passage. This is exemplified in Figure 4a, showing a layer of gas 68 between the fuel column and the air within the chamber 24. This layer of gas, which collects as shown in Figure 4a, is a particular aid in instigating combustion and combatting ignition lag. With reference to Fig-- ure 4a, it will be apparent that, when aspark forms between the electrodes 22 and 35, vaporization of a portion of the fuel will spray into and then from the chamber 24 a mixture of activated gas from the layer 68 and air. Within the intermediate chamber 24, such a mixture of activated fuel and air may be so rich that combustion will not be initiated therein, in which event combustion will take place entirely outside the chamber 24. On the other hand, if the mixture is not too rich, combustion may be initiated within the chamber. In either instance, the presence of the activated fuel will hasten flame starting and flame propagation and will permit satisfactory engine operation even if the cylinder compression is below ignition value for the particular fuel being used in the absence of activation.

when conditions exist as indicated in Figure 4a, the material first discharged through the passages 25a, 25b, and 250 will comprise the activated fuel mixed with air and burning to aid flame propagation. Immediately following this advancing flame will be the remainder of the atomized fuel, itself enhanced by activated materials developed because of the presence of the spark.

Referring to Figure 5, I show a fuel supply means well adapted to use with the spark injector of Figure l or with those to be hereinafter described. This system is designed to maintain a constant, but adjustable, pressure on the fuel delivered to each spark injector of the engine. It consists of a header 18 with four branches leading to four spark injectors, whether disposed on individual cylinders or whether two or more injectors are used with each cylinder. For exam-' ple, each branch 1| may lead to a hose 62.

Each branch preferably includes a restriction metering the rate of flow of fuel to the corresponding spark injector. This restriction may be one of constant diameter, as shown by the orifice plate 12 disposed in each branch, or may be of the variable type, as represented by a needle valve 73 associated with each branch. In some instances, both types of restriction can be used to advantage.

Means are provided for maintaining the header l8 filled with fuel at a. constant, but adjustable, pressure. This may be accomplished by use of a pump 18 intaking from a fuel line 16 extending to a fuel tank (not shown) and discharging through a pipe 11 to the header 18. Suitable means may be provided formulating the discharge pressure of the pump but I prefer to connect this pump in a circulatory system constructed as follows. A chamber 18 is in communication with the header 18 through an opening 88, flow through the opening being restricted by a springloaded valve means 8|, the compression in the spring being adjustable by turning a plug 82 against which the spring bears. l8 communicates with a pipe 84 which returns fuel to the pump 15. correspondingly, a portion of the fuel is continuously circulating from the pump 15 through the header 18, the valve means 8|, and the chamber 18, returning to the intake of the pump. The pressure within the header 18 can be adjusted by changing the loading of the valve means 8| and' it is often desirable to connect the plug 82 to a link 86 leading to the throttle of the engine. In this instance, the speed and power output of the engine arecontrolled by changing the pressure in the header 18, thus changing correspondingly the pressure at which fuel is supplied to each of the spark injectors.

With such a system, a throttled flow of liquid fuel will take place to each spark injector during the exhaust and intake strokes of the engine and, in fact, at all times when the pressure in the cylinder is less than the pressure in the header 18, disregarding the slight differential pressure required to open the spring-loaded check valve 28, The total increment of fuel reaching the capillary passage 3| will be determined by the orifice plates 12. The effective pressure can be varied by controlling-the pressure in the header 18 as previously described, or by simultaneously adjusting the needle valves 18 through a common linkage 88 which, if desired, may extend to the throttle of the engine. In this latter instance,

The chamberthe pressure in the header 18 may, if desired, be maintained constant and the speed and power output of the engine regulated by simultaneous adiustmentof the needle valves 13.

In the systems thus far described, metering of the fuel is accomplished by displacement (Figure 1) or by a system regulating pressure or flow of the fuel (Figure 5). It should be clear, however, that metering can also be accomplished by control of the energy dissipated in the spark,'e. g., by wattage control. The wattage ofthe spark can be controlled by changing the potential, current, or both, or by changing the spacing of the electrodes. As the wattage increases, the eflective fuel-injecting impulse is increased and the invention can be made to discharge a larger increment of fuel into the cylinder. While wattage control can be used with some degree of effectiveness in the embodiment of Figures 1 and 2, it is particularly applicable to systems in which a valve means is provided between the spark chamber and the cylinder. Such systems are exemplifled in Figures 6 to 12, inclusive.

Referring particularly to Figure 6, the spark injector includes a body 88 providing a spark passage 8| communicating with an auxiliary chamber 82 by way of an opening 83, The body 88 is threaded into the cylinder head, diagrammatically indicated at 84, and the lower end of the spark passage 8| is beveled to provide a valve seat 85. A poppet valve 88 is adapted to lose communication between the passage 8| and the cylinder when drawn into engagement with the seat 85 by aspring 81 surrounding a stem 88 of the valve. The construction is such as to hold the valve 86 resiliently closed until the spark-generated pressure within the passage 8| causes the branch lines ll.

valve to open to discharge the high pressure fuel into the cylinder in atomized state.

Fuel is delivered to the passage 8| between periods of injection by flow through a passage 88 controlled by a timed inlet valve I88 to which the fuel is supplied from a suitable source. such as that shown in Figure 5, in which event a nipple I81 may be directly connected to one of the In this embodiment of the invention, the valve I88 is opened at a time, and retained open for a time, determined by a cam I83 which rotates in timed relation with the crank-shaft of the engine. The operative interconnection is shown as including a lever |8l pivoted at I85 to a stationary support and pivoted at I86 to the valve I 88. This valve should be closed during the injection periods. but may be open during all or any portion of the cycle between periods of injection.

The spark is formed between grounded and I high tension electrodes I88 and I 88 to open the valve 86 andinject fuel. Both electrodes may be zbody 88, as shown. the high tension electrode I88 extending through a bushing 8 carried by a sleeve III threaded into an opening 2 of the body 88. A slight turning of the sleeve II can be made to change the length of the gap between the electrodes.

The high tension electrode I88 is connected to a distributor Ill, and a high tension winding H5 as previously described. The wattage of the spark can be changed by changing the potential applied. In this connection, one method of voltage control is illustrated in Figure 6 as including a tapped primary winding 8 including asaaooo .cuit. As previously described, this primary circult includes a make-and-break switch .I I3 actuated by a cam H9. The other side of the primary circuit includes avariable impedance I20- serving as an alternative means for wattage control. This variable impedance may be in, the

form of-a variable choke or variable resistance element. Here, as in Figure 1, the timing of the spark can be adiusted by changing the relative positions of the cam H9 and the make-andbreak switch I I6.

The mode of operation 01' this form of the invention is as follows. Assuming that the spark passage 9I and the passage 99 are filled with liquid fuel, as is also the chamber 92, the spark will form a gas bubble, as previously described, and will establish a steep-wave-front surge. which is transmitted through the fuel column to the valve 96 to open this valve against the action of the spring 91, whereby the fuel will be atomixed into the cylinder'of the engine. The increment of fuel thus injected is determined by the spark wattage. The valve 96 remains open only during the time that suiflcient pressure exits in the passage 9| to force fuel into the cylinder, and it will be understood that various forms of valves can be used to aid atomization, the one shown being merely diagrammatic. During the following strokes of the pistons-oi the engine, the valve I will open to permit re-charge of the spark passage 9I with an amount or fuel corresponding to that injected. If desired, the time during which the valve I00 is open can be adjusted simultaneously with adjustment in wattage. It will be clear that the valve I00 will close prior to the subsequent injection period. i

If the gas bubble produced by the spark contains fixed gases as well as vapors and if the interval between sparks is of such length as to permit a rise or these fixed gases in the passage ill, some gases may rise into the chamber 92,

an intermediate chamber under the control of a suitable valve which may be float-operated, if desired. The amount of fixed gases thus formed will be small and, by proper design, a large part or all of these will be injected into the cylinder by the interveningwail, particularly as the opening 93 thereoiis not much larger than the stem 00. In fact, this intervening wall can be so positioned with respect to the valve 96 as to establish a resonant condition aiding in the retention or this valve in open position during the latter stages of injection;

The form of the invention shown in Figure 7 is quite similar, except that the intake valve is electrically actuated. Here. the corresponding valve is indicated by the numeral I as being of the poppet type, being drawn upward when a winding I26 is energized. During periods oi deenergization, the valve I25 dropsby gravity or spring action to rest on a stop I21. The solenoid winding I26 is energized during periods of injection by connection to one peripheral terminal I26 of an auxiliary distributor I29 providing a rotor I30, This rotor is driven at the same speed as the rotoroi the distributor II4, as suggested by dotted lines Ill, but the phase relationship therebetween may, if desired, be adjusted, as suggested by the dotted arrow I32; The rotor I30 is connected by a conductor I34 with anauxiliary contact I35 of the make-and-break switch I36. The cam I I9, previously described, serves first to brin the auxiliary contact I35 into engagement with an auxiliary contact I31, thus closing the circuit to the solenoid winding I26 and closing the valve I25. Further rotation of the cam II9 moves the auxiliary contact I31 bodily to open the makeand-break contact I36, thus deenergizing the primary winding IIB of the high tension coil and thus generating a high potential in the secondary winding H5 to establish a spark. In the circuit'oi Figure 7, wattage control can be effected byadjustment oi the variable impedance I20 or by suitable control of voltage, shown in this instance as accomplished by a tapped secondary winding II5 feeding the distributor II4. Figure 8 shows an alternative embodiment of the invention using a poppet type valve so arranged that the spark is established relatively close to the point of injection. Here, the spark injector includesa body I providing a bore I5I flared to form a valve seat I52 discharging into the cylinder of the engine. Resiliently mounted in the bore I5] is a poppet valve I53, formed as shown best in Figure 9.- This valve includes a to aid in the combustion. It willv be, clear that,

' system in which the pressures change slowly, such a gas cushion has no substantial effect on the beveled plate I54 sealing against the valve seat I52 when in upper position. Abifurcated shank I55 extends upward and carries pins I56. A

spring I51 is positioned in a counterbore 158 and is compressed between these pins and theshelf of the counterbore, thus urging the valve I53 resiliently upward. A flattened lug I60 extends downward between the bifurcations to prevent t sirning of the valve I53 with respect to the body I 0.

In this embodiment of the invention. the spark passage is formed inside the bore I5I between the bifurcations and is indicated by the numeral I 62. A grounded electrode I63 extends inward steep-wave-front system of the invention. Even portion I69 which is threadedly received by a portion of a bore I10 through which the electrode I66 extends centrally. By turning the member I68, the distance across the gap between the electrodes can thus be chan ed. This may be accomplished by any suitable means, such as the linkage I12 shown diagrammatically and which may extend to the throttle or other control for the engine.

nected to a fuel supply, as previously indicated.

Fuel is supplied to this embodiment in any one of the ways previously described, the flow being through a spring-loaded check valve I18 preventing any return flow of fluid during the injection period. Energization of the electrode IE6 is preferably by way of any of the high tension circuits previously described, though this embodiment'of the invention is particularly adaptable for wattage control.

The construction shown'in Figure 8 is particularly advantageous in view of the closeproximity between the spark and the point of injection intothe cylinder. That portion of the fuel column on the engine side of the spark will be effectively atomized and spewed into the cylinder when the spark is established. In addition, the proximity of the gap to the beveled plate I 54'insures immediate opening of the valve I58 by the pressure wave. Here again, that portion ofthe pressure wave which moves upward in the passage I92 may be reflected downward to reach the beveled plate I54 during the subsequent portions of the injection period to aid in the retention of the a 16 I98 with a spring-loaded inlet valve I94 con- 'In this embodiment of the invention, the interior spaces of the body I15 may be filled with fluid fuel, including particularly the spark passage I92. when a high potential is delivered to the electrode I88 by any of the means previously valve in open position. It should be understood that it is within the contemplation of the invention to use acoustic means in actuating the valve means of the spark injector. This is exemplifled in the previous discussion with respect to the exit valve means through which injection takes place. It will also be apparent that the negative pressure wave (or wave of rarefaction) which follows each pressure wave in an acoustic systemcan be made to aid in the actuation of the inlet valve, for example, the valve I13 in Figure 8, by appropriate design of the system to take advantage'of the acoustic properties of the system. Some of the fundamental principles involved in opening a valve in response to a rarefaction following the reflection of a positive pressure wave are set forth in my copending application, Serial No. 389,030, filed April 17, 1941, nowPatent 2,355,618.

Another poppet type spark injector is shown in Figures and 11, in which the body is in-- dicated by the numeral I15 and provides a, bore I16 formed as previously indicated with reference to Figure 8. Thepoppet type valve is indicated by the numeral I18 and is constructed as best shown in Figure 11. It provides a valve member I19 adapted to seat against a valve face I89 under the resilient action of a spring I8I compressed between I15, as previously set forth. These pins are carried at the upper end of a hollow shank I 84providing a plurality of openings I85 communicating between the interior and exterior thereof at a position just above the valve member I19.-

The grounded electrode in this embodiment is" indicated by the numeral I81 and projects upward from the valve-member I19. The high tension electrode is indicated by the numeral I88 and is carried by a bushing I89 suitably secured to the body I15. A sleeve I99 extends downward fromthe bushing I89 inside the shank I84 of the valve member I18 and terminates opposite the openings I85, just above the valve member I19. In this embodiment of the invention, the spark passage is defined by the skirt I99 and is indicated generally by the numeral I92. The upper end of this passage communicates through an opening pins I82 and a ledge of the body I described, the spark will form and the valve member I19 will be propelled downward under the influence of thesteep-wave-front pressure surge. At the same time, the gap between the electrodes I81 and I88 will be slightly lengthened, though this will usually be insuiflcient to disrupt the arc. which will persist until the applied voltage is reduced to terminate the injection. The general mode of operation is similar to that described with reference to Figure 8 and will be apparent from the previous remarks.

Figure 12 shows a pintle-type spark injector including a body 299 providing a bore 2" equipped with liner inserts 292 with spaced edges defining vertical channels 298. A valve member 294 provides ribs 295 slidablein these channels to prevent turning of the valve member during its up and down motion. A bifurcated pintle 298 extends downward from the member 294 to provide a passage 291 bounded at its lower end by a valve element 298 providing conical surfaces engageable with a valve seat 299. Electrodes 2I9 and 2 form a gap within the passage 291, the electrode 2| I being adjustably mounted in a manner described with reference to Figure 8. A compression spring 2| 3 urges the valve member 294 resiliently downward. A spring-loaded check valve 2I5 conducts fuel from a suitabl source to the upper-end of the bore 29I whence it can flow downward through the loosely fitting channel-rib arrangement to the spark passage 291 so as to submerge the electrodes between periods oi" injection.

The electrode 2 can be energized by any of its'tendencyto close the valve by that portion of the pressure wave which moves upward and acts on an area of equal size. This upwardmoving pressure wave acts against the large surrounding area of the bottom of the valve 294 to cause lifting thereof. The momentarily high pressure within the lower end of the bore 29I will propel fluid from and into the cylinder in highly atomized state.

The forms of the invention exemplified in Figures 6, 7, 8, l0, and 12 can discharge fuel directly into the combustion zone of'the engine or they. may be equipped with hoods. such as shown in Figures 1 and 2, to provide an intermediate chamber from which the fuel is discharged into the combustion zone. V

In general, it will be recognized that the invention can be embodied in widely diiferent forms. of which those exemplified are illustrative. In all instances. the spark will be formed within the fuel while this fuel is in a space sufficiently confined to permit momentary high pressures which are utilized for injection and atomization. This will be true whether the spark is only partially or completely submerged. In addition-the spark should be formed within a mass offuel in the liquid phase and. by the term "liquid fuel," it

. 17 should be understood that I am not limited to a fuel wholly in liquid state asthe inventioncan well be used to inject liquid fuelcarrying'sus pended solid fuel, such aspowdered coal. etc.

It will be further apparent that the invention provides for a very complete mixing of the injected fuel'and the air in the cylinder, so much so that substantially all of the air mixes with the fuel to form the combustible mixture, in contradistinction to conventional Diesel engines in which not more than about 80% of the air-is used to support combustion. Y While the invention has been described with particular reference to injection of fuel into the cylinder of a compression ignition engine, it can also be used for the injection of fuel into other heat engines, as well as for more general purposes of atomizing. propelling. or metering liquids, for intermittently discharging increments of fluid from a space into some other space 01'' zone for any one of a number of functions.

Various changes and modifications can be made without departing from the spirit of the invention as defined in the appended claims.

I claim as my invention:

1. A method of metering small quantities of liquid from a passage into a space, which method includes the steps of: confining a body of said liquid within said passage against rearward movement therein, the confinement against as distinct from pressures arising from substantial combustion immediately adjacent such' sparks; and supplying additional liquid to said passage in amount substantially corresponding to the amount of liquid expelled from said passage by said electric sparks.

2. A method of metering small quantities of liquid from a passage into a space, which method includes the steps of: pumping increments of said liquid intermittently into said passage; establishing a series of electric sparks within the liquid in said passage in timed relationship with the pumping of said increments of liquid into said passage, each of said electric sparks establishing a pressure surge within said passage by gasification of a portion of the liquid, as distinct from initiating combustion'thereof at the spark position, to aid in the forward discharge of increments from said passage into said space; and restraining the liquid in said space against substantial rearward movement upon occurrence of such pressure surges.

3. A method of forming intermittent high velocity Jets issuing forwardly from a passage, which method includes the steps of: intermittently supplying a liquid to said passage: intermittently establishing an electric spark withinsaid liquid insaid passage between periods of supply of liquid to said passage, each electric spark gaslfying a; portion of the liquid as distinct from effecting" combustion thereof at the spark position and eaclfelectric spark establishing a pressure surge within said passage of sumcient intensity to form one of said intermittent Jets; and restraining the liquid in said passage 1 surges produce said intermittent Jets issuing lorwardly from said passage.

4. A method as defined in claim 3, including the step of expelling at least a portion of the gasified material from said passage as a part of said jets. 5. A method for injecting fuel into the combustion zone of a heat engine through a. passage communicable with said zone, which method includes the steps of delivering a small amount of liquid fuel to said passage and trappin same therein against reverse fiow; establishing an electric spark in said passage within said liquid fuel'to build up a steep-wave-front pressure surge having a peak pressure substantially higher than the pressure existing in said combustion zone; and delivering an increment of fuel to said zone from said passage under the influence of said pressure surge.

6. A fuel injection method for injecting atomized fuel into the cylinder of an internal combustion engine through a passage cominunicable therewith, which method includes the steps of: intermittently charging said passage with liquid fuel during that portion of the cycle of said engine between injection periods; and intermittently establishing electric sparks within the liquid fuel in said passage between the intermittent periods of charge of fuel to said passage, each of said sparks serving to gasify a portion of the fuel in the absence of a combustionsupporting gas immediately adjacent the spark and each of said sparks serving to produce a pressure surge sufficient to jet atomized fuel from said passage into said cylinder.

7. In combination in an injection device: walls defining a space with an inlet means and an exit means; supply means for intermittently supplying increments of liquid to said space through said inlet means; electrode means in said space and spaced from each other to form a gap, the increments of liquid intermittently supplied to said spaceby said supply means being suflicient to intermittently fill said gap at least in part with a body of said liquid, said body being liquidcontinuous and extending in said gap. from one electrode means toward the other electrode means; and means for intermittently applying a potential across said gap in timed relationship with said means for intermittently supplying said liquid to said space and sufilcient to form a spark through said body of liquid in said gap and gasify .at least a portion thereof to establish a steepwave-front pressure surge resulting substantially solely from such gasification to discharge an increment of said liquid from said space through said exit means.

8. In combination in an injection device: walls 00 defining a confined space with an inlet means and an exit means; supply means for supplying liquid to said space through said inlet means; electrode means in said space forming a gap in communication with the liquid supplied to said space by said supply means. said supply means acting to supply sufficient liquid to fill said gap at least partially with said liquid; means for energizing said electrodes to establish a spark within said liquid in said gap to gasify a portion of said liquid and establish a steep-wave front pressure surge resulting substantially solely from the spark-induced gasification and of suflicient intensity to discharge an increment of the liquid through said exit means; and means for varying against substantial'rearward movement upon octhe wattage of said spark to control the extent said exit means.

9. In combination in an apparatus for intermittently discharging increments of material into a zone: walls defining a confined space providing an exit means through which said material may be discharged into said zone; means for supplying to said space a liquid capable of form ing vapors and fixed gases when subjected to the action of an electric spark; electrode means in said space providing a gap, said supply means intermittently filling said gap at least partially with a body of said liquid, said body of liquid being liquid-continuous and extending in said gap from one electrode means toward the other; means for establishing a potential difference between said electrodes each time said supply means at least partially fills said gap with said body of liquid. such potential differences being of sufficient magnitude to establish a series of electric therein to gasify at least a portion of said body of liquid to form said vapors and fixed gases and build up a series of steep-wave-front pressure surges resulting substantially solely from sparkinduced gasification and in timed relation with the wave-front pressure surges in timed .relation with the desired incremental discharge of material from said space .into said zone; and means for removing from an upper portion of said confined space any fixed gases formed by said spark which are not expelled from said space through said exit means.

10. In combination in a fuel injection system for injecting an increment of fuel into the combustion zone of a heat engine: walls defining a passage containing liquid fuel; electrode means in said passage defining a. gap at least partially filled with liquid fuel, said gap containing insufiicient combustion-supporting material to cause ignition and burning of the fuel while in said gap upon establishment of a spark between said electrode means; means for impressing a potential difference across said electrode means sufficient to form a spark withinsaid liquid in said gap to build up a pressure surge in said passage; and means for conducting an increment of fuel from said passage to said combustion zone while moving under the influence of the pressure surge generated bysaid spark.

11. A combination as defined in claim 10, in which said last-named means includes a capillary space of such small cross-sectional area that liquid fuel will not drain therefrom into said combustion zone.

12. A combination as defined in claim 10, in which said last-named means includes means defining an intermediate chamber communicating with said passage and providing one or more openings for jetting the increment of fuel into said combustion zone.

13. A method of injecting fuel into the comthe absence of sufiicient oxygen in said electrode gap as will support combustion in such gap.

14. In combination in a device for injecting fuel into the combustion zone of a heat engine: walls defining a confined space; electrode means in said space defining a gap; means for delivering liquid fuel to said confined space in amount suificient to bridge said gap at least partially; means for establishing a spark between said electrode means to traverse the liquid fuel in said gap, said spark being formed in the absence of sufilcient combustion-supporting medium in said gap to ignite and burn the fuel therein; and an exit means communicating between said confined space and said combustion zone, said spark producing a pressure surge in said confined space of sufficient magnitude to eject at least a portion of the fuel in said confined space as a fuel charge into said combustion zone through said exit means.

15. In combination in a device for injecting fuel into the combustion zone of a heat engine:

' walls defining a confined space andan exit means communicating between said confined space and said combustion zone; electrode means in said confined space, there being a. gap between said electrode means; means for establishing a series of sparks across said gap in timed relationship with the operation of said heat engine; and supply means for intermittently delivering increments of liquid fuel to said confined space between the times of occurrence of said sparks, each increment of liquid fuel supplied by said supply means being sufilcient to force liquid fuel into said gap to form a liquid-fuel bridge contacting one of said electrode means and extending at least partially across the gap as a continuous liquid fuel body whereby each spark is formed within such continuous liquid-fuel body in said gap in the absence of sufiicient combustion-supporting mediiun in said gap to ignite and burn the liquid-fuel bridge in said gap, each spark being of sufficient intensity to form sparkactivated gaseous products adjacent'said gap and to establish a steep-wave-front pressure surge in said confined space of sufilcient magnitude to eject an incremental fuel charge into said com-' bustion zone through said exit means. said gap being spaced from said exit means in such manner as to expel a portion of the activated gaseous products produced by a given one of said sparks as a part of the incremental fuel charge ejected by such spark and to retain a. portion of such activated gaseous products within said confined space adjacent said exit means whereby such retained portion is the first to be expelled into said combustion zone as a part of a subsequent incremental fuel charge created by a subsequent spark.

16. In combination in an injection device: walls defining a confined space providing a small atomizing discharge opening through which material may be discharged from said confined space into a reception space; supply means for introducing an increment of liquid material to said confined space to substantially fill same to a position fldiacent said'atomizing discharge opening; means for establishing a spark in submerged position in the liquid material in said-confined space and at a position spaced from said atomizing discharge opening-to establish a steep-wavefront pressure surge of sufficient intensity toexpel and atomize at least a portion of the liquid material in said confined space adjacent said atomizing discharge opening, said spark-establishing means including spaced electrode means in said passage providing a gap in said submerged position. said gap containing the liquid material to the exclusion of any substantial amount of a combustible gas; and means for preventlng'dissipation of said pressure surge to said supply means.

17. In combination in an injection device for injecting increments of fuel into a combustion zone: walls defining a small substantially-capillary passage opening on a spark zone providing an exit portion communicating with said combustion zone; two electrode means in said spark zone spaced to provide a gap adjacent said exit portion; supply means for introducing a column of liquid fuel into said passage in amount sumcient to at least partially bridge said gap with a body of said liquid fuel, said body being liquidcontinuous and extending from one electrode means toward the other; and means for establishing an intense electric spark in said gap through said liquid-continuous body to gasify a portion of the body of fuel and establish a steepwave-front pressure surge in said passage, said surge being produced substantially solely by said gasification and being of sufficient magnitude to eject from said exit portion and atomize into the combustion zone a portion of said liquid fuel and at least a portion of the gaseous products produced by the spark-induced gasification of said body of fuel. 4 i

18. In combination in a fuel injection system for injecting increments of fuel into a combustion zone of a heat engine: walls defining a confined space; electrode means forming a gap in said confined space; means for establishing a series of sparks in said gap; a supply means for supplying liquid fuel to said confined space at periods of time between the establishment of said sparks in said gap and at such rate as to at least partially fill said gap before each spark is established therein with a liquid-continuous body of said liquid fuel extending from one electrode means toward the other, each spark extending through said liquid-continuous body of fuel and gasifying a portion thereof to build up in said confined space a pressure surge induced substantially solely by said spark-induced gasification and of sufiicient intensity to discharge an increment of said fuel from said confined space 4 into said combustion zone; and a check valve for conducting liquid fuel from said supp y means to said confined space and substantially prevent ing reverse fiow of said liquid fuel, said supply means comprising a pressure source of said liquid fuel supplying same to said confined space when the pressure therein is sufiiciently low to permit flow through said check valve from said pressure source to said confined space and said pressure source including means for adjusting the pressure acting to move liquid fuel through said check valve to vary the incremental amounts of fuel discharged into said combustion zone.

19. In combination in a device for injecting small increments of material into a zone of relatively high pressure: walls defining a confined space and an exit means communicating between said confined space and'said zone of relatively high pressure; electrode means in said confined space and providing a gap; means for establishing a series of sparks across said gap; and a relatively low pressure metering pump for intermittently delivering increments of the material in liquid state to said confined space between the times of occurrence of said sparks, each-increment of liquid material thus supplied to said confined space being sufliclent to force some of this liquid material into said gap to contact said elecpartially fill said gap with a body of said liquid,

trode means and extend at least partially across said gap as a continuous liquid body whereby each spark is formed within such continuous liquid body in said gap, each spark being of sufficient intensity to gasiiy at least a portion of the continuous liquid body in said gap and to establish a steep-wave-front pressure surge in said confined space, said pressure surge resulting substantially solely from such gasification and being of higher pressure than the discharge pressure of said metering pump and being of suflicient pressure to expel through said exit means and into said zone of relatively high pressure an increment of the material, the amount of this increment being controlled by the increment of liquid material as metered by said metering D p.

20. In combination in an injection device: walls defining a confined space providing an exit means; two electrode means spaced to form a gap in said confined space; an inlet valve; supply means for supplying liquid to said confined space through said inlet valve and in amount sufiicient to submerge one electrode means and at least said body being liquid-continuous; and means for establishing a spark in said gap traversing said liquid-continuous body to gasify at least a portion thereof and build up a spark-induced pressure surge in said confined space and result ing substantially solely from such gasification to \discharge an increment of said liquid from said confined space through said exit means because of said pressure surge, said inlet valve preventing return fiow of liquid toward said supply means when said pressure surge is established.

21. A combination as defined in claim 14, in which said exit means comprises a pressureoperated valve means opening to provide a restricted passage to said combustion zone and providing a surface closely adjacent said gap, and in which said fuel delivery means includes means for supplying liquid fuel to said confined space in amount suificient to form a liquid-continuous bridge between said gap and said surface of said valve means and contacting said surface, said spark establishing a pressure wave moving through the liquid-continuous bridge to reach said surface and open said valve means.

22. In combination in a device for injecting fuel into a combustion zone: walls defining a. small elongated passage providing an exit portion communicating with said combustion zone; two electrode means spaced from each other substantially longitudinally of said passage to form a gap in which a series of sparks can be established; a supply means for introducing liquid fuel into said passage in amount sufficient to submerge periodically only one Of said electrode means and to fill only partially said gap whereby a portion of said gap is filled with a liquidcontinuous body of fuel having a boundary surface, the remaining portion of said gap containing a body of gaseous products produced by a previous spark. such body of gaseous products extending from the other electrode means to the boundary surface of said body of liquid fuel in said gap whereby said gap contains a liquidgas interface traversing the path of a spark established between said electrodes and in said gap: and means for establishing a series or intense electric sparks in said gap, each spark traversing "both the liquid-continuous body of fuel in said gap and the body of gaseous prod.- ucts therein, each spark gasifying a P rtion of said liquid-continuous body of fuel to form said gaseous products and producing a pressure surge in said passage resulting substantially solely from such gasification and of sufllcient magnitude to elect from said exit portion into said combustion zone an increment of liquid fuel and at least a portion of the gaseous products in the gap when the spark was formed.

23. A combination as defined in claim 14, in

which said spark-establishing means includesmeans for intermittently establishing a plurality of said sparks. and in which said fuel delivery means includes means for delivering increments of the liquid fuel to said confined space in timed relationship with said sparks.

24. In a device for injecting increments of fuel into a combustion zone. the combination of: walls defining a confined space; supply means for slipplying to said confined space a liquid fuel capable of forming vapors and fixed gases when subjected to the action of an electric spark; two electrode means spaced to provide a gap in said confined space, said supply means periodically filling said gap at least partially with a liquid-continuous body of said fuel extending from one,-

being produced substantially solely by such gasification; and means for expelling from said confined space under the influence of such pressure surges an atomized portion of said liquid fuel and at least a part of the vapors and fixed gases formed by said sparks.

25. A method for injecting fuel into the com-- bustion zone of an internal combustion engine through a passage communicable with said zone, which method includes the steps of: delivering to and trapping in said passage a small amount' of liquid fuel; establishing an electric spark in said passage within 24 saidliquid fuel at a position spaced from the point of delivery of said fuel to said combustion zone and in the absence of a combustion-supporting gas immediately adjacent the spark to vaporize a portion of said liquid fuel and build up a steep-wave-front pressure surge of suiilcient peak pressure to force an increment of fuel into said combustion zone from said passage, said pressure surge being sufllcient to force into said combustion zone as a part of the fuel increment a portion of the liquid fuel lying in said passage between said spark and said point of delivery to said cylinder; and delivering at least a portion of the fuel vaporized by said spark to said combustion zone from said passage as a part of the fuel increment.

ALBERT G. BODINE, JR.

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